date

Standard excerpt:

date represents a timePeriod that starts at midnight of a specified day and lasts for 24 hours. The value space of date is the set of Gregorian calendar dates as defined in 5.2.1 of [ISO 8601]. The base type of date is timePeriod. date is generated from timePeriod by setting the value of the duration facet equal to "PT24H" (24 hours). The lexical representation for date is the reduced (right truncated) lexical representation for timePeriod: CCYY-MM-DD. No left truncation is allowed. An optional following time zone qualifier is allowed as for timePeriod. To accommodate year values outside the range from 0 to 9999, additional digits can be added to the left of this representation and an preceding "-" is allowed.

Examples: